A dynamical mechanism for the hairpin diagram

Summary

Based on the nonvalence quark-antiquark and gluon constituent structure of mesons we give a reasonable dynamical mechanism which can induce the hairpin diagram without violating the well-observed OZI rule. We calculate the hairpin amplitudes of$D^0 \to \overline K ^0 \eta$ and$\overline K ^0 \eta '$ normalized by$D^0 \to \overline K ^0 \pi ^0$ and have found that the hairpin diagram can give rise to substantial contributions to the decays where a meson with aSU(3) flavor singlet component is involved in the final state. In this scenario, we also obtain the branching ratio of$D^0 \to \overline K ^0 \phi$ as 0.55% in comparison with the experimental data of 0.83%.